DS-4189 Enhance configuration by environment variables

dspace-services/src/main/java/org/dspace/servicemanager/config/DSpaceEnvironmentConfiguration.java

@@ -0,0 +1,95 @@
+/**
+ * The contents of this file are subject to the license and copyright
+ * detailed in the LICENSE and NOTICE files at the root of the source
+ * tree and available online at
+ *
+ * http://www.dspace.org/license/
+ */
+package org.dspace.servicemanager.config;
+
+import java.util.HashMap;
+import java.util.Map;
+
+import org.apache.commons.configuration2.MapConfiguration;
+import org.apache.commons.lang3.StringUtils;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * Bash does not allow environment variables that contain dots in their name.
+ * This Configuration loads environment variables that contains two underlines after
+ * each other and replaces those with dots. E.g.: dspace__baseUrl will be read as
+ * dspace.baseUrl.
+ *
+ * Most of this file was copied from org.apache.commons.configuration2.EnvironmentConfiguration.
+ *
+ * @author Pascal-Nicolas Becker -- dspace at pascal dash becker dot de
+ */
+public class DSpaceEnvironmentConfiguration extends MapConfiguration {
+
+    private static Logger log = LoggerFactory.getLogger(DSpaceEnvironmentConfiguration.class);
+
+    /**
+     * Create a Configuration based on the environment variables.
+     *
+     * @see System#getenv()
+     */
+    public DSpaceEnvironmentConfiguration() {
+        super(getModifiedEnvMap());
+    }
+
+    public static Map<String, Object> getModifiedEnvMap() {
+        HashMap<String, Object> env = new HashMap<>(System.getenv().size());
+        for (String key : System.getenv().keySet()) {
+            // ignore all properties that do not contain __ as those will be loaded
+            // by apache commons config environment lookup.
+            if (!StringUtils.contains(key, "__")) {
+                continue;
+            }
+
+            // exchange any occurance of "__" with a single dot.
+            String lookup = StringUtils.replace(key, "__", ".");
+            if (System.getenv(key) != null) {
+                // store the new key with the old value in our new properties map.
+                env.put(lookup, System.getenv(key));
+                log.debug("Found env " + lookup + " = " + System.getenv(key) + ".");
+            } else {
+                log.debug("Didn't found env " + lookup + ".");
+            }
+        }
+        return env;
+    }
+
+    /**
+     * Adds a property to this configuration. Because this configuration is
+     * read-only, this operation is not allowed and will cause an exception.
+     *
+     * @param key   the key of the property to be added
+     * @param value the property value
+     */
+    @Override
+    protected void addPropertyDirect(String key, Object value) {
+        throw new UnsupportedOperationException("EnvironmentConfiguration is read-only!");
+    }
+
+    /**
+     * Removes a property from this configuration. Because this configuration is
+     * read-only, this operation is not allowed and will cause an exception.
+     *
+     * @param key the key of the property to be removed
+     */
+    @Override
+    protected void clearPropertyDirect(String key) {
+        throw new UnsupportedOperationException("EnvironmentConfiguration is read-only!");
+    }
+
+    /**
+     * Removes all properties from this configuration. Because this
+     * configuration is read-only, this operation is not allowed and will cause
+     * an exception.
+     */
+    @Override
+    protected void clearInternal() {
+        throw new UnsupportedOperationException("EnvironmentConfiguration is read-only!");
+    }
+}

dspace-services/src/main/java/org/dspace/servicemanager/config/DSpaceEnvironmentConfigurationBuilderProvider.java

@@ -0,0 +1,33 @@
+/**
+ * The contents of this file are subject to the license and copyright
+ * detailed in the LICENSE and NOTICE files at the root of the source
+ * tree and available online at
+ *
+ * http://www.dspace.org/license/
+ */
+package org.dspace.servicemanager.config;
+
+import java.util.Collections;
+
+import org.apache.commons.configuration2.builder.BasicBuilderParameters;
+import org.apache.commons.configuration2.builder.combined.BaseConfigurationBuilderProvider;
+
+/**
+ * Configures DSpaceEnvironmentConfiguration. Reuses BasicConfigurationBuilder and its parameters.
+ *
+ * @author Pascal-Nicolas Becker -- dspace at pascal dash becker dot de
+ */
+public class DSpaceEnvironmentConfigurationBuilderProvider extends BaseConfigurationBuilderProvider {
+
+    /**
+     * Creates a new instance of {@code BaseConfigurationBuilderProvider} and
+     * initializes all its properties.
+     */
+    public DSpaceEnvironmentConfigurationBuilderProvider() {
+        super("org.apache.commons.configuration2.builder.BasicConfigurationBuilder",
+                null,
+                "org.dspace.servicemanager.config.DSpaceEnvironmentConfiguration",
+                // this probably contains much more than we need, nevertheless reusing it is easier than rewriting
+                Collections.singleton(BasicBuilderParameters.class.getName()));
+    }
+}

dspace/config/config-definition.xml

@@ -8,6 +8,13 @@
      https://commons.apache.org/proper/commons-configuration/userguide/howto_combinedbuilder.html
 -->
 <configuration>
+    <header>
+        <providers>
+            <provider
+                    config-tag="dspaceenv"
+                    config-class="org.dspace.servicemanager.config.DSpaceEnvironmentConfigurationBuilderProvider" />
+        </providers>
+    </header>
     <!-- Configurations in this section override one another.
          Earlier values take precedence, and override any values in later config files -->
     <override>
@@ -21,6 +28,9 @@
         <system/>
         <!-- Load Environment variables (does not automatically reload) -->
         <env/>
+        <!-- Load Environment variables that contain two underlines in their names, and exchange those underlines with a
+             dot, as Bash does not allow variables that contains dots in their names.-->
+        <dspaceenv/>
 
         <!-- Allow user to override any configs in a local.cfg -->
         <!-- Any properties in this config will override defaults in dspace.cfg (or any included *.cfg file) -->